Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Usable endurance (after reserve)
4.25
Still-air range at that endurance
468
Total endurance (no reserve)
5.00
Groundspeed used
110
Fuel held for reserve
7.5
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How to use this
- 1Enter usable fuel (gal).
- 2Enter fuel burn rate (gal/hr).
- 3Enter true airspeed (kt).
- 4Enter headwind (negative for tailwind) (kt).
- 5Enter required reserve (min).
- 6Read your usable endurance (after reserve) on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
Endurance and range planning is where fuel exhaustion accidents get made, almost always by pilots who used total fuel capacity instead of usable fuel, or ignored the reserve requirement. This tool takes usable fuel (not total, since unusable fuel sits below the pickup and can't be counted), subtracts your required reserve (45 minutes day VFR, 30 minutes night VFR under most interpretations, more for IFR), and converts the remaining burnable fuel into both flight time and still-air distance at your planned true airspeed.
Worked example
Using the values the calculator loads with:
Inputs
- Usable fuel: 50 gal
- Fuel burn rate: 10 gal/hr
- True airspeed: 120 kt
- Headwind (negative for tailwind): 10 kt
- Required reserve: 45 min
Results
- Usable endurance (after reserve): 4.25
- Still-air range at that endurance: 468
- Total endurance (no reserve): 5
- Groundspeed used: 110
- Fuel held for reserve: 7.5
What each field means
Inputs
- Usable fuel (gal)
- The usable fuel used in the calculation, measured in gal. Starts at 50 gal so you have a working example on load.
- Fuel burn rate (gal/hr)
- The fuel burn rate used in the calculation, measured in gal/hr. Starts at 10 gal/hr so you have a working example on load.
- True airspeed (kt)
- The true airspeed used in the calculation, measured in kt. Starts at 120 kt so you have a working example on load.
- Headwind (negative for tailwind) (kt)
- The headwind (negative for tailwind) used in the calculation, measured in kt. Starts at 10 kt so you have a working example on load. Accepted range: -50–100 kt.
- Required reserve (min)
- The required reserve used in the calculation, measured in min. Starts at 45 min so you have a working example on load.
Results
- Usable endurance (after reserve)
- Returned as a length of time and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Still-air range at that endurance
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Total endurance (no reserve)
- Returned as a length of time. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Groundspeed used
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Fuel held for reserve
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Why usable fuel and not total fuel capacity?
Unusable fuel sits below the fuel pickup point in the tank and cannot be drawn under any attitude — it's a certified figure in the POH, typically 1-3 gallons per tank. Using total capacity instead of usable overstates your real endurance by that amount every single flight, which compounds risk on longer legs.
How much reserve do I actually need?
14 CFR 91.151 requires 30 minutes reserve for day VFR and 45 minutes for night VFR at normal cruise, while 91.167 requires enough IFR fuel to reach the destination, then the alternate if required, then 45 minutes more. Many pilots plan a full hour reserve regardless of the legal minimum as a personal margin.
Does burn rate change with power setting?
Yes, significantly — a burn rate at 75% power can be 20-30% higher than at 55% power for the same airplane. Use the burn rate that matches your actual planned cruise power setting from the POH performance charts, not a generic average, especially for longer cross-countries.
What about climb fuel and taxi fuel?
This calculator assumes a single cruise burn rate for simplicity; real flight planning subtracts taxi/runup fuel and climb fuel (which burns more per hour and covers less ground) before applying the cruise burn to the remaining distance. For short trips these deductions matter more proportionally than on long cross-countries.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
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Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Fuel Endurance & Range Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/fuel-endurance-range
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/fuel-endurance-range" target="_blank" rel="noopener">Fuel Endurance & Range Calculator — RevenueLab</a> (2026).</p>
Source: [Fuel Endurance & Range Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/fuel-endurance-range) (2026).